RFR: 8296072: CertAttrSet::encode should write into DerOutputStream [v2]

[Weijun Wang]

> The argument of the `CertAttrSet::encode` interface method is modified from `OutputStream` to `DerOutputStream`. All its implementations are modified the same way.
> 
> `OutputStream` is still used by `sun.security.x509.Extension::encode(OutputStream os)` because it's inherited from `java.security.cert.Extension`. The method is now marked final to avoid accidental override.
> 
> In `CertificateExtensions` and `CRLExtensions`, only `Extension::encode(DerOutputStream out)` is called. It used to call `CertAttrSet::encode` for a known extension and `Extension::encode(DerOutputStream out)` for an unknown one. This makes sure the overridden `encode` methods in known extensions are always called. Now that they have the same argument, there is no need for this check.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  @Override, used imports, copyright years, and a test

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10906/files
  - new: https://git.openjdk.org/jdk/pull/10906/files/237dc8dc..05f129b2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10906&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10906&range=00-01

  Stats: 81 lines in 36 files changed: 25 ins; 35 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/10906.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10906/head:pull/10906

PR: https://git.openjdk.org/jdk/pull/10906